Marion county is located in south Illinois. Marion county has 572.36 square miles of land area and 3.67 square miles of water area. As of 2010-2014, the total Marion county population is 38,922, which has shrunk 6.64% since 2000. The population growth rate is much lower than the state average rate of 3.62% and is much lower than the national average rate of 11.61%. Marion county median household income is $41,783 in 2010-2014 and has grown by 18.61% since 2000. The income growth rate is lower than the state average rate of 22.70% and is lower than the national average rate of 27.36%. Marion county median house value is $68,500 in 2010-2014 and has grown by 27.56% since 2000. The house value growth rate is lower than the state average rate of 34.33% and is much lower than the national average rate of 46.91%. As a reference, the national Consumer Price Index (CPI) inflation rate for the same period is 26.63%. On average, the public school district that covers Marion county is worse than the state average in quality. The Marion county area code is 618.